Just as some nanotreatments have been inspired by nature, others take a lesson from history. We've known about silver's antibacterial properties for thousands of years. The ancient Greeks and Romans put silver coins in their water carriers to keep it safe for drinking.

Now we can create nanoparticles of silver and attach them to cotton fibres. Their small size makes them far more active in controlling bacteria. Nanosilver fabric is already made into socks that claim to cut the cause of smells by killing the bacteria responsible.